Characteristics dependence on confinement structure and single-mode operation in 2-μm compressively strained InGaAs-lnGaAsP quantum-well lasers

The optimum confinement layer structure in 2-μm compressively strained InGaAs-InGaAsP lasers is experimentally studied. Beside the carrier overflow and absorption loss in the confinement layers, the intervalence band absorption and/or Auger recombination play an important role in laser characteristics. More attention should be paid to the confinement structure to reduce the carrier density. We obtained a better laser performance with an energy difference between the bandgap of the optical confinement layer and the laser transition energy of 280-300 meV. A distributed-feedback (DFB) laser operating at 2.043 μm has been realized with the threshold current as low as 6 mA and the maximum output power of 6 mW. The differential quantum efficiency and the characteristic temperature are 16% and 59 K, respectively.